Accurate prediction of band gap for new emerging materials is highly desirable the exploration potential applications. The gaps bulk and monolayer TMDs (MoS 2 , MoSe WS WSe ) are calculated with recently proposed by us GVJ‐2e method, which implemented within DFT framework without adjustable parameters based on total energies only. in very good agreement experimental ones both TMDs. For MoS direct predicted to be 1.88 eV, 1.57 2.03 1.67 eV correspondingly, TMDs, indirect 1.23 ), 1.09 (MoSe...

Abstract We have performed a theoretical study of the electronic band structure, density states, dielectric function and absorption coefficient isostructural BaSi 2 , BaGe SrGe compounds by means different ab initio methods. All materials are found to be indirect band‐gap semiconductors displaying almost equal dispersion bands close gap region. The energy gaps 0.83, 0.57 0.44 eV estimated for respectively. Analysis in comparison with data other semiconducting silicides indicates its...

In this part we present results of our ab initio calculations indicating that dispersion the bands near gap region for different phases WO3 (namely, ε-WO3, δ-WO3, γ-WO3, β-WO3, orth-WO3, α-WO3, and hex-WO3) is rather close. The rapid increase in absorption coefficient starts at lower energy range α-WO3 hex-WO3 than other accordance with calculated band gaps. An oxygen vacancy has turned out to decrease by 0.50 eV shift room temperature γ-WO3 phase. We have also traced changes caused...

The structural, electronic, and optical properties of II--IV--V${}_{2}$ (II $=$ Be, Mg, Zn, Cd; IV Si, Ge, Sn; V P, As) chalcopyrite-type ternaries have been theoretically investigated from first principles. compounds demonstrate semiconducting behavior, with the direct-band gap ranging about 0.2 to 2.2 eV, except for Be-containing materials, which indicate an indirect gap. band gaps in II--IV--P${}_{2}$ are always larger than corresponding ones II--IV--As${}_{2}$. All characterized by...

In the first part [D. B. Migas et al., J. Appl. Phys. 108, 093713 (2010)] electronic and optical properties of different phases WO3 have been considered. this we present results our ab initio calculations which clearly show that all Magnéli tungsten oxides WOx (namely, W32O84, W3O8, W18O49, W17O47, W5O14, W20O58, W25O73) are characterized by metal-like properties. Their band structures display an energy gap in valence just below Fermi level. We discuss how addition (removal) oxygen atoms to...

By means of first principles calculations, we have investigated the band structures different phases higher manganese silicides ($\mathrm{Mn}{\mathrm{Si}}_{x}$ with $x$ ranging from 1.73 to 1.75). In this family, ${\mathrm{Mn}}_{11}{\mathrm{Si}}_{19}$, ${\mathrm{Mn}}_{15}{\mathrm{Si}}_{26}$, and ${\mathrm{Mn}}_{27}{\mathrm{Si}}_{47}$ been found behave like degenerate semiconductors and, at same time, metals because Fermi level stays partly in energy gap valence close its top. The...

Band structure calculations for β-FeSi2 have been performed by the linear muffin-tin orbital method within local density approximation scheme including exchange and correlation effects. A detailed analysis of conduction valence band around high-symmetry points has shown existence a quasidirect gap in material. It is experimentally confirmed that between threshold energy optical interband transition 0.73 eV first direct with appreciable oscillator strength at about 0.87 there region which low...

Our theoretical findings demonstrate for the first time a possibility of band-gap engineering monolayer MoS2 crystals by oxygen and presence vacancies. Oxygen atoms are revealed to substitute sulfur ones, forming stable MoS2−xOx ternary compounds, or adsorb on top atoms. The substituting provides decrease band gap from 1.86 1.64 eV transforms material direct-gap an indirect-gap semiconductor. surface adsorbed up 0.98 depending their location tending metallic character electron energy bands...

We report ab initio results for the ground-state properties, band diagrams, density of states, and dielectric functions ${\mathrm{Ca}}_{2}Z$ $(Z=\mathrm{Si},$ Ge, Sn, Pb) both in orthorhombic cubic structures. The calculations are performed by means total energy ultrasoft pseudopotential full potential linearized augmented plane wave methods within local generalized gradient approximations. estimated difference cohesion shows structure to be stable phase. also demonstrate that these...

The band structure and magnetic properties of cubic (3C) hexagonal (6H) polytypes silicon carbide doped with 3d transition metals have been studied by ab initio calculations. We demonstrate that for 3C-SiC Cr Mn produce half-metallic ferromagnetic solutions at both (Si C) substitution sites, but different moments, while SiC:Fe remains paramagnetic. A similar situation has observed 6H-SiC; however, Fe on the Si site low concentrations leads to a ordering.

Abstract A detailed study of structural, electronic and optical properties II–IV–N 2 ternary compounds (II = Be, Zn; IV Si, Ge) has been performed by means ab initio density functional theory calculations. The germanium containing were found to be direct‐gap semiconductors with gaps 3.37 eV 1.67 for BeGeN ZnGeN , respectively, oscillator strength direct transition comparable GaN. Two other silicon are characterized indirect 5.19 (3.32) BeSiN (ZnSiN ). Crystal structure being orthorhombic...

We have performed first-principles calculations in order to analyze the influence of spatial orientation on electronic band structure and optical properties hydrogenated germanium quantum wires. A confinement-induced direct gap appears for (110)-oriented wires, whereas (100)- (111)-oriented wires are characterized by an indirect gap. For same wire-effective size, anisotropy fundamental ${E}_{g}$ with respect wire is observed. imaginary part dielectric function shows a pronounced peak visible...

Results of our ab initio calculations have revealed changes in electronic properties Ca2Si semiconducting silicide when reducing dimensionality from bulk to slabs and, eventually, nanowires. In the case bulk, is found be a direct band-gap semiconductor with value 0.30, 0.60, and 0.79 eV by using generalized gradient approximation, modified Becke–Johnson exchange potential screened hybrid functional, respectively. We also identified that among Ca2Si(001), (010), (100) surfaces one has lowest...

The structural, electronic and magnetic properties of BeSiAs(2) BeGeAs(2) chalcopyrite ternary compounds doped with manganese were investigated by means ab initio calculations. It was found that substitution Be atoms Mn increases the lattice constants both provide acceptable mismatch conventional Si, Ge GaAs substrates. In spite increase spin polarization upon doping, possess antiferromagnetic (AFM) ordering impurity in group II position whereas ferromagnetic (FM) is obtained case an IV position.

The interband optical spectra of the semiconducting β phase iron disilicide (β-FeSi2) were investigated in energy range from 0.5 to 5.0 eV. dielectric function and other functions deduced ellipsometric experiments calculated within local-density approximation by using semirelativistic linear muffin-tin orbital method. Reasonable agreement between measured data has been obtained.

Abstract Self‐consistent electronic property simulation of hexagonal CrSi 2 , MoSi and WSi is performed within the local density approximation using semirelativistic linear muffin‐tin orbital method. They are deduced to be narrow‐gap semiconductors with indirect band gaps 0.29,0.07, 0.07 eV, respectively. The effective masses holes electrons in disilicides same order. close free electron mass there a certain reduction appropriate values from chromium tungsten disilicides. Carrier mobility...

We present both theoretical and experimental investigations of electronic optical properties isostructural $\ensuremath{\beta}\ensuremath{-}{\mathrm{FeSi}}_{2}$ ${\mathrm{OsSi}}_{2}$ by means a full-potential linear augmented plane wave method measurements. report also ellipsometric reflectance measurements on samples polycrystalline osmium disilicide prepared mechanical alloying. From ab initio calculations these compounds are found to be indirect band-gap semiconductors with the...

By means of ab initio calculations we have revealed a newly discovered Ca3Si4 compound to be semiconductor. It is characterized by an indirect transition 0.35 eV. A peculiar dispersion the last valence band and first conduction band, displaying loop extrema, has been found. This feature leads large anisotropy mobility holes electrons. We also present dielectric function this material in comparison with data for another semiconducting calcium silicide Ca2Si.

By means of first principles calculations we show that morphology TiO2 nanowires in the rutile phase turns out to be important their stability and band gap engineering. The most stable ⟨001⟩-oriented are found display {110} facets while thermodynamically favorable with ⟨110⟩ axis characterized by {001} facets. Our results clearly demonstrate appearance {100} shape ⟨001⟩ orientation leads a sizable reduction gaps, however, it does not cause shift absorption edge lower energy range. Presence...

Abstract A detailed study of electronic properties tungsten dioxide (WO 2 ) has been performed by means the projector‐augmented wave method. Two phases were considered: stable monoclinic, which was characterized as a metallic one, and high‐temperature metastable orthorhombic, found to be semiconductor with an energy gap about 0.6 eV. We also show possibility that oxygen vacancies in monoclinic oxide providing WO 1.75 stoichiometry can result semiconducting behaviour this compound well.

Electronic band structure calculations of Nowotny ``chimney-ladder'' isostructural ruthenium and osmium silicides related germanides have been performed by the linear muffin-tin orbital method within local density approximation. Both found to be direct gap semiconductors with energy gaps 0.41 0.95 eV in ${\mathrm{Ru}}_{2}{\mathrm{Si}}_{3}$ ${\mathrm{Os}}_{2}{\mathrm{Si}}_{3},$ while a competitive indirect-direct character about 0.3 0.9 ${\mathrm{Ru}}_{2}{\mathrm{Ge}}_{3}$...